Abs first evolved 380 million years ago in armoured fish

Washington: Researchers have discovered a 380 million year old armoured fish in north-west Australia which has miraculously preserved musculature.

Through this study, scientists are hoping to better understand how neck and abdominal muscles evolved during the transition from jawless to jawed vertebrates.

The Gogo Formation, a sedimentary rock formation in north-western Australia, has long been famous for yielding exquisitely preserved fossil fish. Among other things it contains placoderms, an extinct group that includes some of the earliest jawed fish.

A few years ago, an Australian research team work led by Prof. Trinajstic made the discovery that these fossils also contained soft tissues including nerve and muscle cells.

"High contrast X-ray images were produced thanks to a powerful beam and a protocol developed for fossil imaging at the ESRF," Sophie Sanchez, one of the authors, from the ESRF and Uppsala University, said.

"This is unique in the world and has enabled us to "reconstruct" some fossilised muscles and document the muscles of neck and abdomen in these early jawed fish, without damaging or affecting the fossilised remains," she said.

These early vertebrates prove to have a well-developed neck musculature as well as powerful abdominal muscles - not unlike some human equivalents displayed on the beaches of the world every summer.

Living fish, by contrast, usually have a rather simple body musculature without such specialisations.

"This shows that vertebrates developed a sophisticated musculature much earlier than we had thought" says Per Ahlberg, co-author of the project.

The paper describing the discovery has been published in the journal Science.